i'm just wondering if somebody (dont know why im a really nice person) put something in my fill hole 
Seriously, nobody would do that.
Why even think that? Offroading is a hobby of breakage. Plus, anyone who knows how to open up the fill plug and knows what a piece of something would do to your diff wouldn't do that. That's more trouble than somebody is willing to go to for a chuckle.
Post up pics.
